Composite profiles of steel have been known for a long time. Those profiles can make up assemblages of girders by themselves or with flat or contoured elements. The composite profiles can serve as as posts or as other elements in construction waterway equipment, maritime gates, embankments or dikes.
Composite profiles of steel may also be used for the construction of buildings.
For utilization in the form of posts, composite profiles are needed which have not only with a large friction surface, but also an elasticity and rigidity sufficient for pile driving and the stress exercised on it, after the posts are put into service. Moreover, when used as supporting elements in buildings, for example, the composite profiles must be resistant to corrosion, must possess satisfactory supporting power and must be fire-resistant.
In order to render the profiles resistant to corrosion, whatever the ultimate use may be, the elements can be galvanized or otherwise metallized or coats of paint are applied. All these processes require preliminary cleaning of the metallic surfaces by way of scraping or by sand or shot blasting at considerable expenses for equipment and personnel.
One possibility for the making of composite profiles lies in assembling H-form girders from flat or contoured side elements by welding the wings or by joining them with the aid of hooks and spurs, with which the flats or contoured are respectively provided. These junctions are formed by an engaging double hook and the spurs of the wings with which the flats and side contoured are respectively supplied. The seams formed by the inter-engagement of the hooks and spurs nevertheless, need welding, especially when used as posts for pile driving.
It is known that composite profiles which are used as supporting elements in the construction of buildings, can be furnished with a concrete filling, which confers upon them an increased resistance to fire and increases their supporting force. On the other hand, welding lateral sheets to the wings of the girders which is done with a minute care, assures a rigorous water-tightness. When the profile is filled with water It will have an unequalled resistance against fire. Besides, in order to reduce the pressures which exist in the interior of the sections filled with water, separate circuits of small heights have to be envisaged. This method is a very difficult one. In any event, the cooling of composite profiles, which serve as element of support, with water is hardly practiced.
Another difficulty which arises in the course of using composite profiles is that the geometrical tolerance increases during production of the girders, the flats or contoured lateral members and the junctions; and generally, greater efforts are needed for assembling the elements which form the composite profile in series production. This is especially true in the case of long elements.